Conventionally, computer monitors receive Video Graphic Array (VGA) signals and display images accordingly. To upgrade video quality, Digital Visual Interface (DVI) and High-Definition Multimedia Interface (HDMI) specifications have been developed for displaying high quality video. HDMI, for example, is capable of concurrently processing audio/video signals, has been widely adopted, and has become the mainstream of high quality video display.
A conventional high-end computer monitor has dual VGA video ports, which are also known as D-sub. VGA is used for analog signal transmission. Dual VGA video ports are commonly referred to as a two-analog-port (2A) or one-analog-plus-one-analog-port (1A+1A) structure. Referring to FIG. 1, the high-end computer monitor (not shown) has a display controller 100 having dual VGA video ports for receiving two VGA signals 102 and 104, which are then outputted as an output signal and displayed on the monitor. In accordance with traditional standards of the display industry, port switching of dual VGA video ports must be completed within 2 seconds.
As HDMI prevails, high-end computer monitors are now equipped with multiple HDMI ports and a VGA video port for digital and analog transmissions, respectively. For instance, a high-end computer monitor has a VGA video port and two HDMI ports, which is referred to as a one-analog-plus-two-digital (1A+2D) structure since VGA transmits analog signals and HDMI transmits digital signals. Referring to FIG. 2, the high-end computer monitor (not shown) has a display controller 200 conforming to 1A+2D transmission standards. The display controller 200 has a VGA video port and two HDMI ports for receiving a VGA video signal 202 and two HDMI inputs 204 and 206, respectively, to produce an output signal to be displayed on the monitor. In following prior requirements of the display industry on 2A computer monitors, port switching process of the display controller 200 of the 1A+2D computer monitor is also expected to complete within 2 seconds. To those skilled in the related field, it is understood that, generally, VGA video port detection takes 0.5 second, and HDMI port detection takes 2 seconds or even longer. As a result, time needed to complete detection of 1A+2D ports according to the conventional art is at least 4.5 seconds, which is far longer than the traditional 2 second expectation.
For the foregoing reasons, there is a need for a solution that can quickly switch ports.